It is the antithesis of all false preachers, as they are described in Galatians (Gal. 6:13): “They desire to have you circumcised that they may glory in your flesh.” So all false teachers seek their own glory, although they give lip service to the glory of God. … Yet the Gospel proclaims the glory of God alone. “The heavens are telling the glory of God” (Ps. 19:1), not their own glory. The glory of God is that God alone is wise, righteous, and the Redeemer. It follows that we are foolish and lost sinners, because the glory of God is not set forth unless we ourselves are confounded. The papists do not want this confounding, yea, they ascribe a part of righteousness to their own glory, and therefore it cannot bear the Gospel. The Holy Spirit convicts the whole world of sin (John 16:8) and proclaims the righteous Christ and His glory alone. It is the office of an evangelical preacher to proclaim the glory of God alone.
“Lectures on Isaiah: Chapters 40-66” in LW, 17:172–173.